15 out of 19 Whitehall departments, including the Home Office, do not have numbers on EU employment, according to the FT article, based on polling by Labour MP Chuka Umunna's campaign group Vote Leave Watch, which aims to hold Brexit campaigners to account on their referendum promises.

The four departments that do keep track of EU citizens employ 968 Europeans. 816 are at one department — the Department of Health.

Labour's Umunna told the FT: "This news makes a mockery of Amber Rudd's proposals, which were already unnecessary, unworkable and calculated to cause division in our society. She needs to drop these plans and get her own house in order before seeking to force new regulations on British business."

In a separate interview with the FT, former cabinet minister William Hague called for a simple system of EU work visas post-Brexit. He said: "We're not expecting to be in the single market without freedom of movement but we would expect on this basis tariff free trade across all sectors."